Sensor Logger Watch Reliability

Due to the limitations of iOS and WatchOS, Sensor Logger’s companion watch app may not always be reliable. However, if you take the following steps, it will improve the robustness of the connection between the watch and the phone, ensuring the data from the watch is logged correctly.

Always Enable Heart Rate

Enabling the heart rate sensor is the only way to ensure the watch app works in the background — even though you may not be interested in the heart rate data itself. For example, even if you are only interested in the wrist motion, please also enable the heart rate data and grant the relevant permissions.

Grant Sensor Logger Permission to Access Heart Rate Data

Double-check that you have granted Sensor Logger access to the heart rate data on both the watch and the phone. This is a read-only permission, so Sensor Logger will not write anything to your health database. Even with the permission granted, Sensor Logger will always only access your heart rate data in real-time during a recording session.

Check on the watch with these steps

On the phone, you also need to check:

Start a Workout Just Before Starting a Recording

If you start a workout session on the watch, and then switch to the Sensor Logger app and start the recording, this usually leads to better reliability.

Do Not Start a Workout During a Recording Session

Do not start a workout session when Sensor Logger is running. This includes both manually starting a session, such as via the fitness or workout app, or indirectly, such as via a Focus Mode. This will interfere with Sensor Logger’s own Workout session, which is needed to ensure proper background privileges.

Set Return to Clock to 1 Hour

Setting “Return to Clock” to 1 hour improves the chance Sensor Logger will stay reliably in the foreground. You can check this under the Settings app on your watch. Go to General > Return to Clock. Either set it to 1 hour for all apps, or specifically set Sensor Logger’s to 1 hour.